Coding apparatus and position-finding apparatus and method

ABSTRACT

A computer-implemented method for determining the position of a lift cabin in a lift shaft with the aid of a coding device, in which method is at least one of a section of the code band and the bearing device is recorded with an optical detection device as a pixel image in which the pixel image is larger than the position marker, the pixel image is processed and a binary code is decoded by means of an algorithm and converted into a position indication, a checksum of the position marker, which is formed by at least one of the binary code and grayscale values of the position marker, is compared to a predetermined value, and one of a barcode and a 2D code calculated from the position indication using an inverse of the algorithm and is compared with at least one recorded row outside of the position marker.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/EP2014/002765 filed Oct. 14, 2014, which designated the UnitedStates, and claims the benefit under 35 USC §119(a)-(d) of EuropeanApplication No. 13004910.9 filed Oct. 14, 2013, the entireties of whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a coding device for marking positionsin a lift shaft and for determining the position of lift cabins in thelift shaft, and to a computer-implemented method for determining theposition of a lift cabin in a lift shaft with the aid of a codingdevice, and to a position-determining device.

BACKGROUND OF THE INVENTION

The prior art, for example EP 0 722 903 B1, has disclosed a method inwhich a lift cabin is displaced in the lift shaft along a code band,wherein the lift cabin comprises a detector and, when the detector comesacross an image pattern applied to the code band, the detector comparesthe image pattern with a reference pattern and derives information forthe controller from the identified pattern.

SUMMARY OF THE INVENTION

An object of the present invention is to be able to provide a code band,a position-determining method and a position-determining device whichenable an increased level of safety in operating the lift.

The present invention firstly makes available a code band in the case ofwhich discrete positions are admittedly marked, but can, however, beprovided in a density such that the lift cabin can read out its positionpractically permanently. The control unit for controlling the lifttravel, that is to say its closed-loop and/or open-loop control, canthus be provided permanently with the information relating to thecurrent position of the travel cabin, and there are practically nodistances along which the travel cabin is driven “blind”, that is to saywithout concrete position information, and cannot react until it meets amarking which is intended, for example, to cause the cabin to brake.This measure enables a high degree of safety in operating the lift. Inaddition, the present invention offers reliable and safe operation ofthe lift cabin, because the type of coding device and ofcomputer-implemented method for determining the position enablesinspection options, redundancies and plausibility checks by means ofwhich high safety standards can be achieved. In particular, it is alsopossible to read out positions even when the code band is, for example,soiled and it is therefore no longer possible to read out all theinformation held there.

A further advantage of the present invention consists in that preciselyin connection with the use of a coding device according to an exemplaryembodiment of the present invention having bearing devices, there is, inaddition, the possibility of being able to take account of the subsidingof a newly constructed building when evaluating and determining theposition of the lift cabin, even of being able to correct thedetermination of position. Newly erected buildings mostly have theproperty that they “subside” with time, that is to say instances ofcompression can occur in the building in the course of time because ofthe high weight loads. This effect can occur precisely with highbuildings, which mostly have a lift. It is a particularly problematicfeature of this effect in the construction of buildings that not allparts of the building respond uniformly thereto. In particular, as arule, the lift structure in which the travel cabin is mounted to bedriven is not affected thereby, or is at least only partially affectedthereby. In such a case, the partial compression of the building wallmeans that the travel cabins are also displaced with respect to theframe of the lift shaft. Such a correction, which is likewise enabled bythe invention, can compensate this phenomenon of the subsidence of abuilding. In particular, it is possible thereby to increase the safetyand reliability in operation of the lift.

The inventive coding device serves for marking positions in a liftshaft, and for determining the position of lift cabins in the liftshaft. It comprises a code band which is, for example, suspended andfastened in the lift shaft on the roof of the building. The code band ismounted to move in the lift shaft via a bearing device. When, forexample, the building subsides and is partially compressed inwardly, thecode band can appropriately move downward together with the ceiling ofthe building and yet continue to hang freely, because it is mounted tomove inside the bearing devices and not held fast. Consequently, thefreely hanging code band must also not bend or be compressed duringsubsidence of the coding. The markings are arranged discretely along thelength of the code band and can for example be provided equidistantly.The markings can be designed as a barcode, but particularly preferablyas 2D code (two-dimensional code). Firstly, such a 2D code visuallydelivers a particularly advantageous, simplified detection, but also ahigh density of coding options.

In principle, a barcode can be arranged in a row, but a 2D code(two-dimensional code) can also be provided accordingly. A 2D code isnormally designed as a matrix, it being possible for the individualmatrix elements to form bright or dark, that is to say the values 1 or0. One or more rows can mark a discrete position as such. It isparticularly advantageous for this type of markings that they can notonly be easily detected and read out, but also can be decoded by meansof an algorithm and be processed mathematically. The advantage islikewise achieved thereby that it is possible to avoid complicatedcomparisons of images with reference patterns which, on the one hand,can be more prone to error but, on the other hand, also requirecomputers of high graphic computing power and, moreover, necessitatememories with high capacity for storing the reference patterns. Inaccordance with the invention, the mathematical algorithm can beevaluated with the aid of a computer, and, if appropriate, even by meansof a simple microcontroller or microprocessor. This advantage in timealso enables the markings to be evaluated very quickly so that even inthe case of high marking density, the travel cabin can be permanentlyinformed of its position in the lift shaft during its trip.

The markings comprise a position marker, from which the position can beread out or which marks the position along the code band. Overall, thereexists an algorithm with which this decoding can be undertaken and whichis also invertible. In particular, a unique assignment of a position toa position marker, possibly also to part of the position marker, ispossible. The bearing device is arranged in such a way that it is alsodetected. The bearing device comprises a marking itself, which markingcan be read out and wherein information can be gathered from themarking. If this marking comprises a barcode or 2D code, these can beformed e.g. in respect of the number of matrix elements thereof in sucha way that each marking can in fact also only be assigned to a specificposition and does not occur twice on the code band at differentlocations. However, the markings which are applied directly to thebearing device initially do not mark a position on the code band but,independently thereof, a position in the lift shaft. Since the buildingmay subside over time, there may be displacements between specificpositions in the lift shaft and the borne code band.

In the case of an equidistant arrangement in accordance with oneexemplary embodiment of the present invention, the evaluation can becarried out in a particularly simple manner because the distance betweentwo marking rows is known as a matter of principle. Inter alfa, thissimplifies e.g. an extrapolation which is applied if two positionsincluding associated timestamps are stored and a third position isintended to be deduced from a further time indication. The timestamp ineach case provides information about when the corresponding position wasreached and read out. In order to carry out the extrapolation, theevaluation method takes account of, for example, the speed or the speedprofile of the lift cabin in the corresponding time intervals.

So that the bearing devices can be uniquely identified as such, theycan, in particular, be formed with a single color in the color of a codecolor. Moreover, the selection of a dark color, in particular black, asa color lends itself to this end. Otherwise, incorrect detections couldoccur more easily in the case of dirtying of the bearing device. Theone-color form enables a particularly simple assignment. If a code coloris used, the evaluation can take place in a particularly simple mannerbecause the evaluation device can also take into account the bearingdevice, to the extent that this is in the detection field, whendetecting the code band and also read it out. Then, there is no need fordistinction as to which algorithm needs to be applied because, inprinciple, the same evaluation prescription applies to the code band andthe bearing device.

The computer-implemented method according to the present invention fordetermining the position of the lift cabin comprises image processingand analysis method.

Here, the image processing method comprises the following steps:

A section of a code band and/or of the bearing device is recorded withan optical detection device as a pixel image consisting of pixels,wherein the recorded section is selected to be so large that itcomprises at least one more row than the position marker. Furthermore,the image processing comprises the step of the pixel image beingprocessed, in particular being assigned to a detection grid, and pixelsof the pixel image preferably being combined with the aid of their colorand/or position in order to be able to read out the barcode and/or 2Dcode of the marking.

The analysis method in turn comprises a position pattern analysis, achecksum test and a full pattern test. In the position pattern analysis,the position marker is identified on the basis of the part of themarking for characterizing the position marker. Then, a position code isidentified in the detection grid, in particular as a barcode and/or 2Dcode, on the basis of the position marker. The position code isconverted to a binary code, whereupon the binary code is decoded bymeans of an algorithm and converted into a position indication and/orinto information as to whether a bearing device has been detected. Thefirst partial method consisting of the image processing and the positionpattern analysis from the analysis method is repeatable at equal timeintervals of the travel in order to obtain position informationcontinuously.

Furthermore, the analysis method comprises a checksum test of theposition marker, by means of which the position marker is checked inrespect of plausibility, by virtue of a checksum being formed by way ofthe binary code and/or the grayscale values of the position marker andbeing compared to a predetermined value. By way of example, if the valuezero is assigned to black, the checksum can accordingly equal zero.However, since, in general, a dark grayscale value is often detected,even when a black region is detected, the threshold can be adaptedaccordingly to these grayscale values in order to obtain a more reliableevaluation under realistic conditions.

Moreover, the analysis method comprises a full pattern test, wherein abarcode and/or 2D code is calculated from the decoded positionindication on the basis of the inverse of the algorithm, the codecorresponding to the at least one row which was also recorded outside ofthe position marker, and this calculated barcode and/or 2D code iscompared with the at least one recorded row.

In the case of the extrapolation method in particular, it is necessaryfor time information to be available in addition to a positionindication such that possible conclusions can be drawn in respect of theposition at which the lift is situated at a given further instant. Tothis end, it is necessary to assign the instant of the recording to therecording of a pixel image, i.e. provide the latter with a timestamp.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are illustrated in the drawingsand explained in more detail below with an indication of further detailsand advantages.

FIG. 1 shows the reading out of the coding device in accordance with thepresent invention by an optical detector;

FIG. 2 shows a schematic illustration of a camera recording;

FIG. 3 shows a pair of pixel strips;

FIG. 4 shows an extended image pattern;

FIG. 5 shows an image pattern;

FIG. 6 shows a position pattern;

FIG. 7 shows an overall scheme of the computer-implemented method inaccordance with the invention;

FIG. 8 shows a schematic illustration of the image processing;

FIG. 9 shows a schematic illustration of the analysis method;

FIG. 10 shows a schematic illustration of the comparison method; and

FIG. 11 shows a schematic illustration of the correlation method.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a detection device 1 which reads out a code band 2 in alift shaft. Provided for this purpose on the lateral edges of the codeband are position strips 3 which laterally delimit the 2D code 4. Thecoding device comprises the code band 2 and a clip 7: the code band 2 ismounted to move with such clips 7 as bearing device such that it can bedisplaced in a longitudinal direction when, for example, the buildingsubsides with time. The clip 7 comprises a bridge 8 which overlaps thecode 4 and/or the position strips 3. The detection device 1 basicallycomprises two cameras whose detection beams 9, 10 for recording adetection image are likewise illustrated in FIG. 1.

FIG. 2 shows the recorded image section K of the camera, which wasrecorded of the code band 2. The recording 1 overlaps the lateral edgeof the code band 2. Position strips 3 are provided at the outer edges ofthe code band in a longitudinal direction of the code band 2. Theposition strips 3 are completely black in design and are thereforeeasily detected by the detection device and the evaluation method. Theseposition strips 3 likewise provide screening, such that the evaluationmethod is able to detect the region in which the 2D code 4 is to befound. The 2D code 4 is composed of a matrix which has individual matrixelements 5, 6. The matrix element 5 is a bright one, while the matrixelement 6 is a dark one. However, in general, the matrix elements 5, 6do not correspond in each case to a single pixel of the camerarecording. Consequently, it is necessary when processing images toassign recorded pixels to one another in accordance with their positionand their brightness and combine them to form a matrix element. In thecombined image, in turn, a pixel then represents a matrix element.Specified in FIGS. 3 to 6 are sections processed by image processing Band in the case of which camera pixels have been processed to formmatrix elements.

An overall illustration of a computer-implemented method for determiningthe position is illustrated in FIG. 7.

Camera Recording K

The detection device 1 enables optical detection of the markings 3, 4(position strips 3 and 2D code 4) provided on the code band 2. Thecamera (optionally including a plurality of cameras) generally operatesin the infrared region (IR light, wavelength approximately greater than780 nanometers to 1 millimeter), so that in particular, it is alsopossible to avoid interfering influences. If the cabin is traveling inthe lift shaft in which the code band 2 is also suspended, the cabinwill move along the code band, the camera being aligned such that it cancorrespondingly detect the code band. During the trip, the camerarepeatedly takes recordings K of sections of the code band (inparticular, in equal time intervals), compare FIG. 2. Such a pixelrecording can typically comprise 100×24 pixels and be recorded as agrayscale image (for example 12-bit image). At the same time, in thepresent case a clock or a timer is provided which assigns a timestampdepending on the camera recording, that is to say a time informationitem, when the recording is finished. This timestamp later enablesevaluation of the images when further information is known, that is tosay, for example, individual positions at specific instants, speed ofthe lift cabin or acceleration of the lift cabin.

Extrapolation Method E

The aim of the overall method from FIG. 7 is to determine the positionof the lift cabin, specifically at different instants, making itpossible, as already described, for the individual positions also to begiven by timestamps. In a further method step, a check is made after thecamera recording K as to whether there have already been determined in amemory two positions in relation to which two timestamps are alsopresent. If this is the case, the position can be determined at afurther, third instant (extrapolation). If the cabin has not carried outany uniform movement, the extrapolation can be performed, ifappropriate, by taking account of the speed, known from the open-loop orclosed-loop control of the cabin, of the lift cabin, or the accelerationof the lift cabin. Given uniform movement of the lift cabin, the speedthereof can be determined from two positions and their timestamps, thatis to say the time information item, once these positions have beenreached. If there is no change in this speed, the position cancorrespondingly be obtained therefrom at a further, third, instant. Ifthe lift cabin accelerates in this time, or if the lift cabin is brakedin this time, this must be appropriately taken into account. These data,relating to the acceleration and, if appropriate, also to the speed, canbe retrieved and read out in embodiments of the invention by the controldevice of the travel cabin (open-loop or closed-loop control). If fewerthan two positions are stored after carrying out the camera recording,the next method step is adopted without extrapolation taking place.

The precondition for carrying out the extrapolation method E is that atleast two positions and three timestamps are stored. The two positionsserve for being able to determine a path difference between the twopositions. If two further timestamps are available, each of which isrespectively assigned to one of the two positions, it is also possibleto determine the time difference required to reach the other positionproceeding from one of the two positions. The third timestamp isrequired in order, finally, to be able to determine the further positionto be extrapolated. Thus, before actually carrying out the extrapolationmethod, a check needs to be made as to whether this precondition that atotal of two positions and three timestamps are stored is satisfied.

Image Processing B (FIG. 8)

The next method step consists of image processing. A grayscale image hasbeen recorded in the camera recording. It is also conceivable, inprinciple, to immediately record a black and white image, the more so asthe 2D code 4 imprinted on the code band 2 is designed as a barcode or2D code, and therefore basically consists of only two colors orbrightnesses. However, it must be taken into account that it is notalways possible to exactly detect the same brightness values of asurface by influences from ambient light, deposits on the code band,slight differences in distance or in detection angle. Black surfacesthen, as the case may be, appear more or less gray. In order to be ableto take account of this effect, it is advantageous to record a grayscaleimage and to decide with the aid of the color, here with the aid of athreshold value of a grayscale or brightness, whether the detectedsurface or the detected pixel is to be assigned to a dark or a brightregion with reference to a barcode or a 2D code. If appropriate, thisthreshold value can also be set as variable, thus likewise in principleenabling readjustment. For one thing, the recorded images can thereby beconverted in principle into a 1-bit image. Secondly, it is to be bornein mind that a type of image detection or assignment to a screen is alsoperformed in the image processing.

In this way, it is possible to separate (in the present case) two pixelstrips which comprise 2×24 pixels and whose longitudinal extent runsalong the columns S (compare FIG. 3).

Furthermore, an image pattern and an extended image pattern aregenerated (FIGS. 4 and 5). The extended image pattern is illustrated inFIG. 4 and consists of 8×7 matrix elements in a black and white image,that is to say 1-bit representation. In these generated patterns, thematrix elements are represented in each case as a pixel in a fashioncombined and reduced in size. The extended image pattern in accordancewith FIG. 4 therefore has more rows Z than the image pattern inaccordance with FIG. 5 because, as explained later, the bridge 8 of abearing device or of a clip 7 can comprise three rows. In addition, eachposition marker, which has the complete information relating to a singleposition, comprises three rows in the present exemplary embodiment. Ifappropriate, additional rows may be required for individual evaluationmethods.

The simple image pattern is illustrated in FIG. 5 and has only fiverows, likewise illustrated in black and white, that is to say one-bitrepresentation. The entire 2D matrix pattern comprises ten columns, asshown in FIG. 2. The outer right and the outer left column 11 serve thepurpose of separating position markers, that is to say coherent regionsof the matrix which completely code a separate position, that is to sayof marking where the position starts and stops. This is required so thatin the event of random recording of an image it is clear where theposition is marked and that parts of two different position markers arenot being evaluated together, something which could result in anincorrect position indication. The rows of the matrix are arrangedwithout spacing from one another in the present exemplary embodiment,thus enabling a higher density of the markings.

FIG. 6 shows a position pattern with only three rows, that is to say aposition marker with the complete coding of a specific position.

As already described above, the code band is mounted to move in bearingdevices for the movable bearing of the code band which are fastened onthe wall of the lift shaft. These so-called clips 7 overlap the codeband 2 toward the lift cabin (with the bridge 8), that is to say towardthe side on which the marking of the code band is located. The cliptherefore partially covers the code band in principle. At this point,the position would thus not be “detectable” in principle during a camerarecording. Consequently, it is advantageous to detect the clip as such.The inventive coding device is particularly advantageous to the effectthat the clip need not be detected as an image however, but that it cansurprisingly be evaluated together with the code band. To this end, thebridge 8 of the clip, which projects beyond the code band and isdetected, has a coding pattern which corresponds to that of the codeband, that is to say a barcode or a 2D code.

It is particularly advantageous to configure the code mapped on the clipin as simple a way as possible, in particular in a color of the barcodeor 2D code coding, that is to say black or white or bright or dark.Firstly, the production of the clip is thereby simplified. Secondly, theclip can thereby be easily detected, something which is particularlyadvantageous because the construction phenomenon of the subsidence ofbuildings can entail the clip moving relative to the code band when thebuilding subsides over time. The clip then changes its position relativeto the code band upon subsidence of the building. It is thereforeadvantageous to provide only one of the markings with an absoluteposition indication, specifically either the code band or the clip, sothat a comparison can be appropriately carried out. The clip cantherefore be found by a mathematical analysis or the carrying out of analgorithm. This clip identification is performed in the image processingvia the extended image pattern. A pixel-row analysis is performed inwhich the cross sum over the detected matrix elements is formed. In thepresent case, the clip is designed as black, and so a check is made asto whether the cross sum over the matrix elements yields zero. If thisis the case, it can only be a clip which is concerned, since the codingis selected such that other rows cannot have the cross sum 0.

Since it is also known how many rows the clip is using, for example,three rows, its position can also be determined. If, for example, onlyone row is completely black at the upper image edge, the clip iscorrespondingly located in the upper region of the camera recording. Ifall rows of the clip can be detected, it is located at a correspondingpoint in the camera recording K. An immediately adjacent position cantherefore be assigned by a completely mapped position marker. If, in thecase of an embodiment, there is no longer enough space to detect acomplete position marker, it is necessary, if appropriate, to derive theposition of the clip via extrapolation, or to assign the clip anappropriate position. When detecting a clip, it is not always necessaryto assign its exact position; it is always sufficient to assign theclips a position in the same way, for example, with a constant offset,since it is generally necessary to establish only relative distancesbetween the clips, in order to establish, for example, how strongly abuilding has subsided. By way of example, the lower edge of the clip isdetermined with regard to its position in the present case.

Clip Position C

In a further method step, it is established whether an extrapolatedposition has already been generated at all. If it is the case, it isfurther decided whether it was possible to identify a clip and whether aclip pixel position has been obtained. If this is likewise to beanswered in the affirmative, the next partial method is that ofdetermining C the clip position (FIG. 7). With the aid of the priorinformation relating to the clip position, the extrapolation method E isused to extrapolate a position of the clip. If this extrapolatedposition corresponds at least approximately to the clip position, theextrapolated position is output as position and, if appropriate, so alsois an information item as to whether a clip was present or not. Thisinformation item can be designed as a 1-bit information item (clip bit).Finally, the clip is assigned its corresponding position (method stepCP) and output. The clip position itself can likewise be stored and usedlater for a correction when the building has subsided.

If, by way of example, the lift has only just started and for thisreason two positions have not yet been stored, the so-called analysismethod A is firstly carried out.

If a position can be obtained from the detected position pattern and atleast one clip bar is detected in part, the exact position of the clipbar must be extrapolated. Then, the position of the clip bar isgenerally slightly displaced in relation to the detected position. Ifthe clip bar completely covers the position pattern, it may be possibleto extrapolate the new position from the positions stored in the past.By way of example, if the clip bar completely fills a position pattern,it is not possible from the clip bar alone to deduce the positionthereof in the present exemplary embodiment, and so the position must beextrapolated from previously stored data.

Analysis Method A (FIG. 9)

In the analysis method, the image pattern determined by the camera isfirstly used to undertake a checksum test, that is to say a check ismade as to whether the detected matrix elements yield a specialchecksum. In addition, the position marker (FIG. 6) is determined withthe aid of the lateral edges 11, and the position of the recorded imageis determined with the aid of the prescribed algorithm. The calculatedposition serves in the present case to infer with the aid of the inversemethod of the algorithm which further rows border on the positionmarker. These have likewise also been recorded by the camera. Acomparison is then undertaken as to whether these calculated patternsalso correspond to that of the regions bordering on the positionmarkers. These regions, which border on the position marker, thereforedo not need to be used in addition to calculating a position. Dependingon how many of the upper and lower edge regions are indicated inside thecamera recording K, this is, as the case may be, not even possiblestraight away. If these generated codings correspond to the actuallyrecorded codings, it may be concluded with very high probability thatthe position indication is actually correct. This position can then beoutput (position output OUT in FIG. 7), it likewise being possible,optionally, to perform an additional assignment of the clip positionwhen a clip has been detected. If an extrapolated position has beengenerated, but no clip recorded, the comparison method is carried out.

As already explained above, the position pattern, which has three rowsin accordance with FIG. 6, contains all of the position information.However, the analysis method uses the image pattern which comprises tworows more than the position pattern. It is therefore possible to deducethe two adjacent rows from the position pattern, to which an inversemethod of the algorithm for determining the position can be applied.Thus, a corresponding image pattern to be expected is generated andcompared with the actual image pattern (cf. FIG. 5). In the case of acorrespondence, the established position is the actual position of thelift cabin with a high probability. As can be seen in FIG. 4, a clip barcomprises a width of three rows which, in terms of size, corresponds toa position pattern. Thus, if the clip bar appears in an image pattern,what may occur is that the latter, without the upper and lower row,forms precisely the filtered out position pattern. The clip canaccordingly be identified as such by virtue of the cross sum beingformed over the grayscale values in the pixel image and being comparedto a grayscale threshold.

The clip bar is black in the exemplary embodiment. Since the value zerois assigned to the color black, this yields a cross sum of zero in theideal case as only black pixels are detected. However, what may happenin reality is that, for example, a dark grayscale value is detectedinstead of an ideal black value, and so it is generally advantageous toset the threshold not to zero but to a specific threshold value as afunction of the grayscale values to be expected during the detection. Ifthe clip is only partly in the position pattern obtained from the imagepattern, which is obtained from the image pattern, a deduction about theactual position is nevertheless possible from the identified rows,taking into account the clip position. In the present exemplaryembodiment, the code is selected in such a way that each row is, infact, completely individual and does not occur a second time on the codeband. If a clip bar is detected and it only makes up part of theposition pattern, the uppermost or lowermost row of the image patternmust likewise form part of the clip bar in the present example. This canalso be taken into account in the full pattern test of the analysismethod.

The high level of safety is ensured because it is not only thedetection, which may, as a matter of principle, be afflicted by errors(be it by dirtying, additional reflections or other erroneousdetections), that is taken into account, but because part of thedetection previously not taken into account is resorted to on the basisof inverting the algorithm and deductions in respect thereof are made.

Comparison Method V (FIG. 10)

Apart from the image pattern, the extrapolated position is required forthe comparison method (FIG. 7). The image pattern to be expected isdetermined from the extrapolated position alone and compared with thatactually recorded. If the comparison is exactly correct, it can bededuced therefrom that the correct position has actually been found, andthe extrapolated position is output as the position indication OUT.However, it can happen that although the extrapolated position and theactual position correspond, the recorded image can nevertheless beincorrectly processed because, for example, the code band is soiled atsome points, or because other disturbing influences have played a role.If the code is selected such that only one or only a few matrix elementsdo not change from one row to the next, it is possible to tolerate aslight deviation in the case of a few matrix elements, and neverthelessto assume that the extrapolated position is actually present andcorresponds to that recorded. In the present case, this can, forexample, be assumed whenever fewer than four matrix elements deviate. Itis particularly advantageous to this end to select the coding forreasons of safety such that the coding can deviate strongly from one rowZ to the next. For example, the algorithm can provide a code in the casethe matrix elements are interchanged in a prescribed way as a functionof the position of the row, something which can easily be implementedwhen the algorithm is known. However, if the deviation is too large, amethod can be carried out with an acceleration correction. Particularlywhen the lift cabin is accelerated or decelerated while it is travelinguncertainties occur with regard to the extrapolation, since thesechanges in speed in time would need to be detected accurately, and thespeed would have to be detected by integrating the acceleration overtime. For technical reasons, this cannot generally be undertaken soaccurately that deviations would be inconceivable, especially as themarkings, for example, are provided with a spacing of half a millimeter.

An acceleration correction is optionally carried out with a type ofposition variation, this would firstly likewise require the extrapolatedposition indication. The image pattern is now generated on the basis ofthe extrapolated position indication, which has been calculated, as arethe further rows, which directly border on the position marker of thegenerated image pattern. The recorded pattern is thus compared withimage patterns which are to be found one, two or three rows above theimage pattern, since it corresponds to the extrapolated positionindication. If the recorded image pattern exists in this region, it canbe assumed that the position determination has deviated within atolerable limit, and that the extrapolated position is the outputposition. If this comparison also delivers no result, a correlationmethod is carried out. The pair of pixel strips known from FIG. 3 isused to this end.

Correlation Method KV (FIG. 11)

The first requirement is the generated pair of pixel strips (see FIG.3), specifically in each case a current pattern and a pattern previouslyrecorded during the trip. These pixel strips, which have been recordedat different times, are, to a certain extent, laid one over another anddisplaced until agreement is reached. In this case, the determination isdone in accordance with the offset. In addition, a plausibility checkcan be carried out with the aid of the extrapolated position. Since thedetection device comprises two cameras overall, a second comparison canalso be carried out during the correlation method KV with the aid of asecond camera (second camera image K′ in FIG. 7), and examined forconsistency. When this correlation method KV also leads to no consistentresult, a further extrapolation method E which proceeds analogously tothat described above can be carried out once again. When this also leadsto no result, it is necessary to carry out a new camera recording, sinceno position can be determined. If appropriate, a case of emergency isoutput when no position at all can be determined.

It is also conceivable in principle, in particular, to combine theanalysis method, the comparison method or the correlation method withone another in another way, for example in a different sequence.

LIST OF REFERENCE SYMBOLS

-   1 Detection device-   2 Code band-   3 Position strip-   4 2D code-   5 Matrix element-   6 Matrix element-   7 Clip-   8 Bridge-   9 Detection lighting-   10 Detection lighting-   11 Marking columns-   A Analysis method-   B Image processing-   C Determination of the clip position-   CP Clip position assignment-   E Extrapolation method-   K Camera recording-   K′ Second camera recording-   KV Correlation method-   V Comparison method-   OUT Position output

The invention claimed is:
 1. A coding device for marking positions in alift shaft and for determining the position of lift cabins in the liftshaft comprising a code band, wherein: the code band has at least threemarkings, which are arranged along a length of the code band in order tomark discrete positions in each case, the at least three markings areformed as at least one of a barcode and a 2D code, the at least threemarkings are arranged in such a way to form rows, the at least threemarkings are formed in such a way to include a position marker for eachdiscrete position to be marked, the at least three markings aredecodable by way of an algorithm, at least one bearing device isprovided for bearing the code band in the lift shaft that can be movedlongitudinally, the at least one bearing device formed to encompass thecode band at least in part, and formed in such a way to carry a markingwhich is arranged in such a way to cover at least part of the marking ofthe code band in a readable manner when the code band is encompassed atleast in part.
 2. The coding device according to claim 1, wherein themarkings are arranged in such a way to form at least two columns.
 3. Thecoding device according to claim 1, wherein the position markers areembodied in such a way that a discrete position is coded in at least tworows.
 4. The coding device according to claim 1, wherein part of themarking is formed to characterize the position marker.
 5. The codingdevice according to claim 1, wherein the markings are applied at leastone of without spacing and equidistantly on the code band.
 6. The codingdevice according to claim 1, wherein the bearing device has a web inorder to engage over the code band on a side at least one of at whichthe markings are applied and which are to face a detection device. 7.The coding device according to claim 6, wherein the markings of the atleast one bearing device are applied to a web and have a form with onlyone color.
 8. The coding device according to claim 7, wherein the onlyone color is exactly one of the two colors of at least one of the barcode and the 2D code.
 9. The coding device according to claim 8, whereinthe only one color corresponds to a darker code color of the two colors.10. The coding device according to claim 9, wherein the only one coloris black.
 11. The coding device according to claim 1, wherein the atleast three marks form at least as many rows as a number of discretepositions to be marked.
 12. The coding device according to claim 1,wherein the algorithm includes a mathematical function which uniquelyassign a corresponding position to each marking of the position.
 13. Thecoding device according to claim 1, wherein the at least one bearingdevice encompasses an entirety of the code band.
 14. Acomputer-implemented method for determining the position of the liftcabin in a lift shaft on the basis of a coding device according to claim1, further comprising the following steps of: recording at least one ofthe section of the code band and the bearing device with an opticaldetection device as a pixel image (K) consisting of pixels, wherein thepixel image (K) is selected to include at least one more row than theposition marker, processing the pixel image such that pixels of thepixel image are being combined aided by at least one of color andposition in order to be able to read out at least one of the barcode andthe 2D code of the marking, identifying the position marker on the basisof a part of the marking for characterizing the position marker,identifying a position code in a detection grid as at least one of thebarcode and the 2D code, on the basis of the position marker, convertingthe position code to a binary code, and decoding the binary code bymeans of an algorithm and converting into at least one of a positionindication and information as to whether a bearing device has beendetected, wherein the method is repeatable at predetermined timeintervals of a travel of the lift cabin, and wherein the method furthercomprises the steps of: performing a checksum test of the positionmarker by means of which the position marker is checked in respect ofplausibility, a checksum being formed by at least one of the binary codeand grayscale values of the position marker and the checksum beingcompared to a predetermined value, calculating at least one of thebarcode and the 2D code from the decoded position indication on a basisof an inverse of the algorithm, said calculated at least one of the barcode and the 2D code corresponding to at least one row which wasrecorded outside of the position marker, and comparing said calculatedat least one of the barcode and the 2D code with the at least onerecorded row.
 15. The computer-implemented method according to claim 14,wherein a time of the recording is measured and assigned to the pixelimage when the pixel image is recorded.
 16. The computer-implementedmethod according to claim 14, wherein the recording of the at least onesection of the code band is carried out as a grayscale recording. 17.The computer-implemented method according to claim 16, wherein thegrayscale recording is converted into at least one of a black and whiteimage and a 1-bit image on the basis of a grayscale threshold value. 18.The computer-implemented method according to claim 14, whereinrecordings of the at least one section of the code band and the bearingdevice with the optical detection device are carried out repeatedlyduring operation at equal time intervals.
 19. A position determiningdevice for determining the position of a lift cabin in a lift shaft,comprising a detection device for optically reading out markings of acode band and a computer for carrying out the computer-implementedmethod according to claim
 8. 20. The computer-implemented methodaccording to claim 14, wherein processing the pixel image furthercomprises assigning the pixel image to a detection grid.
 21. Thecomputer-implemented method according to claim 14, wherein thepredetermined time intervals are equal time intervals.